diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Tubes / Valves (http://www.diyaudio.com/forums/tubes-valves/)
-   -   pete millet low mu preamp (http://www.diyaudio.com/forums/tubes-valves/204007-pete-millet-low-mu-preamp.html)

tubo 8th January 2012 08:00 AM

pete millet low mu preamp
 
hi,

has anyone built or heard this low mu preamp? does the circuit invert phase? i don't need to much gain in my amps that's why im interested in building this.any input please.thanks

Low-mu preamp

dsavitsk 8th January 2012 08:53 AM

Quote:

Originally Posted by tubo (Post 2851650)
hi, has anyone built or heard this low mu preamp?

Yes to both.

Quote:

Originally Posted by tubo (Post 2851650)
does the circuit invert phase?

Yes

Quote:

Originally Posted by tubo (Post 2851650)
i don't need to much gain in my amps that's why im interested in building this.any input please.

The 6AS7 can be a very noisy tube. Look around for the 12B4 threads -- you can build much the same design with that tube, but it is quieter and more linear.

http://www.diyaudio.com/forums/tubes...nded-grid.html

http://www.diyaudio.com/forums/tubes...stage-amp.html

AJT 8th January 2012 08:54 AM

the 6AS7 has a mu of about 2, it is an inverting type line amp.....

AJT 8th January 2012 08:55 AM

and the 12b4 can be microphonic...be warned....

radiostar 8th January 2012 09:54 AM

My friend made it with 6AS7, works fine for my ears ...


Good luck!

tubo 8th January 2012 10:14 PM

thanks guys,

i think ill just convert the 6v6line amp to cathode follower and see what happens.

Jeffrey Davison 9th January 2012 05:53 AM

4 Attachment(s)
Built one about a year and a half ago. Went with a single transfomer but dual power supplies, one for each channel. Went with a grid choke instead of a grid leak resistor. Geartz hybrid with the rectifiers. Need a touch of gain so went with a 421a. Just a little hum, but not intrusive enough to distract from the music. Just last week I went with DC on the 421a filament with a vccs rectifier/regulator. Also upgraded to Clarity Cap MR on the 10uf output caps, not that the Obligatos were bad, just want a bit more out of this piece. The pics were taken after I finished building it. Rectifier tubes are now a pair of EML 274B mesh plates and went with Shuguang Treasure series 6Ca7 as the old KT77's I had were a tad noisy as a CCS. Treasures were much quiter. VERY happy with the sonics.

JD

radiostar 9th January 2012 02:15 PM

Tidy job!

Congratulations!!!


All times are GMT. The time now is 10:03 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2